There has been described a technology for standardizing 200 volts and 400 volts by comparing a direct-current voltage, which is connected to a commercial three-phase power supply and rectified, with a reference value and operating or stopping a first switching element and a second switching element (e.g., Patent Literature 1). There has been described a technology for storing energy in a reactor and boosting a voltage by continuously setting a period in which a first switching element and a second switching element are simultaneously turned on and off or simultaneously turned on, a period in which only one of the first switching element and the second switching element is turned on, a period in which the first switching element and the second switching element are simultaneously turned on, and a period in which only the other of the first switching element and the second switching element is turned on (e.g., Patent Literature 2).
Concerning a commercial single-phase power supply, there has been described a technology for making it possible to control full-wave rectification and double-voltage rectification and control an input voltage into a wide variety of output voltages by alternately switching two switching elements connected in series (e.g., Patent Literature 3).
Further, there has been described a technology in which boosting chopper units configured by switching elements and reactors inserted in respective phases are connected to a neutral point of a star connecting wire of a multi-phase power supply and the switching elements operate, whereby harmonics are suppressed (e.g., Patent Literature 4).
There has been described a technology for keeping a boosting ratio constant by controlling ON/OFF of a double voltage switch (e.g., Patent Literature 5).